
#include <stdio.h>

#define __STDC_CONSTANT_MACROS

#ifdef _WIN32
//Windows
extern "C"
{
#include "libavcodec/avcodec.h"
#include "libavformat/avformat.h"
#include "libswscale/swscale.h"
}
#else
//Linux...
#ifdef __cplusplus
extern "C"
{
#endif
#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libswscale/swscale.h>
#include <SDL2/SDL.h>
#ifdef __cplusplus
};
#endif
#endif

int main(int argc, char* argv[])
{

    AVFormatContext *pFormatCtx;
    int             i, videoindex;
    AVCodecContext  *pCodecCtx;
    AVCodec         *pCodec;
    AVFrame *pFrame, *pFrameYUV;
    uint8_t *out_buffer;
    AVPacket *packet;
    int ret, got_picture =0;


    struct SwsContext *img_convert_ctx;
    char filepath[] = "rtsp://192.168.90.171/1";
    av_register_all();
    avformat_network_init();
    pFormatCtx = avformat_alloc_context();

    if (avformat_open_input(&pFormatCtx, filepath, NULL, NULL) != 0)////打开网络流或文件流
    {
        printf("Couldn't open input stream.\n");
        return -1;
    }
    if (avformat_find_stream_info(pFormatCtx, NULL)<0)
    {
        printf("Couldn't find stream information.\n");
        return -1;
    }
    videoindex = -1;
    for (i = 0; i<pFormatCtx->nb_streams; i++)
        if (pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO)
        {
            videoindex = i;
            break;
        }
    if (videoindex == -1)
    {
        printf("Didn't find a video stream.\n");
        return -1;
    }
    pCodecCtx = pFormatCtx->streams[videoindex]->codec;
    pCodec = avcodec_find_decoder(pCodecCtx->codec_id);
    if (pCodec == NULL)
    {
        printf("Codec not found.\n");
        return -1;
    }
    if (avcodec_open2(pCodecCtx, pCodec, NULL)<0)
    {
        printf("Could not open codec.\n");
        return -1;
    }
    pFrame = av_frame_alloc();
    pFrameYUV = av_frame_alloc();

    out_buffer = (uint8_t *)av_malloc(avpicture_get_size(AV_PIX_FMT_YUV420P, pCodecCtx->width, pCodecCtx->height));
    avpicture_fill((AVPicture *)pFrameYUV, out_buffer, AV_PIX_FMT_YUV420P, pCodecCtx->width, pCodecCtx->height);

    //Output Info---输出一些文件（RTSP）信息
    printf("---------------- File Information ---------------\n");
    av_dump_format(pFormatCtx, 0, filepath, 0);
    printf("-------------------------------------------------\n");

    img_convert_ctx = sws_getContext(pCodecCtx->width, pCodecCtx->height, pCodecCtx->pix_fmt,
        pCodecCtx->width, pCodecCtx->height, AV_PIX_FMT_YUV420P, SWS_BICUBIC, NULL, NULL, NULL);


    packet = (AVPacket *)av_malloc(sizeof(AVPacket));

    FILE *fpSave;
    if ((fpSave = fopen("geth264.h264", "ab")) == NULL) //h264保存的文件名
        return 0;
    for (;;)
    {
        //------------------------------
        if (av_read_frame(pFormatCtx, packet) >= 0)
        {
            if (packet->stream_index == videoindex)
            {
                fwrite(packet->data, 1, packet->size, fpSave);//写数据到文件中
            }
            av_free_packet(packet);
        }
    }


    //--------------
    av_frame_free(&pFrameYUV);
    av_frame_free(&pFrame);
    avcodec_close(pCodecCtx);
    avformat_close_input(&pFormatCtx);

    return 0;
}
